Preemergence weed control using corn gluten meal

ABSTRACT

Corn gluten meal is used as a natural preemergence herbicide.

.Iadd.This is a reissue of U.S. Pat. No. 5,030,298. .Iaddend.

FIELD OF THE INVENTION

This invention relates to a natural herbicide which may be applied tosoil plots to achieve preemergence weed control as a substitute forchemical herbicides or as a supplement to chemical herbicides to reducetheir concentration in the environment.

BACKGROUND OF THE INVENTION

The use of herbicides to control undesirable weeds in a selectivefashion is commonplace. Chemical herbicides are a large business, andinvolve millions of pounds of herbicide applied directly to the soil onan annual basis. An effective herbicide must not only controlundesirable plants, dubbed weeds, but must also control them in aselective manner so that desired plants will grow. Preemergenceherbicides refer to those which must be applied before the weed emergesfrom the soil.

In recent times, especially since environmental awareness has increased,many herbicides, including many preemergence herbicides have come underdisfavor as chemical pollutants. This is especially true in areas of thecountry where these preemergence herbicides are applied in largequantities. It has now come to be recognized by many groups andassociations, including the Environmental Protection Agency, that thesepreemergence herbicides may have an undesirable poluting effect, notonly on the soil, but on the level of contamination in ground water,etc.

There is, therefore, a real and continuing need to develop naturalherbicides. As used herein natural herbicides refers to herbicides thatcome naturally from available growing, safe substances. One example ofnatural treatments for soil includes biological controls such as theaddition of specific bacteria to accomplish a desired result. Anothermore common example of natural product application to soils would bemanure as a fertilizer.

Natural herbicides would have a distinct advantage in that they would besafe materials, and materials which would not cause any concern forpossible contamination of ground water from runoff of soil movement.

Accordingly, it is a primary objective of the present invention toprovide a natural preemergence herbicide useful in controlling weedssuch as crabgrass, smart weed, barnyard grass, etc.

Another objective of the present invention is to provide a naturalpreemergence herbicide from corn gluten meal extracted from corn meal.

Another objective of the present invention is to provide a natural corngluten meal preemergence herbicide which can be used as a substitute forchemical herbicides or as a supplement to chemical herbicides to reducetheir concentration in the environment.

A still further objective of the present invention is to provide amethod and means of preemergence control of annual grass weeds.

The method and manner of accomplishing each of the above objectives, aswell as others, will become apparent from the description of theinvention which follows hereinafter.

SUMMARY OF THE INVENTION

In accordance with this invention, preemergence weed control isaccomplished by applying to a soil plot, prior to weed emergence, aherbicidally effective amount of corn gluten meal. Corn gluten meal,when applied in this pre-emergence manner functions to selectivelyinhibit annual grassy weeds.

DETAILED DESCRIPTION OF THE INVENTION

As earlier stated, this invention involves preemergence weed control.Preemergence, as those skilled in the art know, refers to weed controlsubstances which must be applied before emergence of the annual grassyweeds, usually in the Spring. There are of course many commerciallyavailable preemergence chemical controls. In accordance with thisinvention, a preemergence weed control which is natural and not subjectto the ordinary environmental risks is provided. The natural weedcontrol substance of the present invention is corn gluten meal. Corngluten meal is a fraction extracted from corn meal. When the corn glutenmeal is applied to a soil plot prior to weed emergence in a small butherbicidally effective amount, it will selectively inhibit undesirableplants such as annual grassy weeds. Plants known to be effectivelyinhibited in a preemergence manner by the application of corn glutenmeal include, but are not necessarily limited to crabgrass, creepingbentgrass, smart weed, barnyard grass, Bermuda grass and tall fescue.The amount of corn gluten meal which can be applied can vary over a widerange, but is generally within the range of a concentration from about 5lbs/1000 sq. ft. to about 40 lbs./1000 sq ft. preferably from about 10lbs./l000 sq. ft. to about 30 lbs/1000 sq. ft. and optimally, to about20 lbs./1000 sq. ft.

The manner of addition of the corn gluten meal is the same as any otherconventional preemergence herbicide and it can be applied by the use ofa conventional lawn fertilizer spreader. It can be in the form of adust, powder, pellets, etc.

Corn gluten meal is a commercially available material extracted fromcorn meal. It is commercially available from many sources such as GrainProcessing Corporation of Muscatine, Iowa, 52761. Generally, as thoseskilled in the art know, corn gluten meal is made by drying the liquidgluten stream separated from corn during corn wet milling processing.While its composition can vary, it commonly contains about 60% proteinand is rich in xanthophills. It is a mixture of protein, lipid,carbohydrate and ash material. While corn gluten meal is known, and hasbeen commercially available, in the past its primary usage has been as afeed substance for use with broilers, etc.

It is important to note in accordance with the present invention thatthe material applied as a preemergence herbicide is corn gluten meal,not corn meal. Corn gluten meal, as earlier stated, differs considerablyfrom corn meal in that it is extracted material made by drying theliquid gluten stream separated from corn during the corn wet millingprocessing. Thus, it represents a fortified material in comparison withcorn meal. Corn meal itself has been tried as a preemergence herbicidefor use in the present invention. Corn meal is somewhat effective, butcorn gluten meal is much more effective.

It is not known precisely why corn gluten meal functions effectively asa natural preemergence herbicide. While applicant does not wish to bebound by any theory, based upon investigations to date, it is believedthat the corn gluten meal when applied to a soil plot, selectively stopsroot development of annual grassy weeds almost precisely at the time ofgermination. As a result, as soon as the plant begins to grow, it willundergo root stress and die. Thus, for some unknown reason, while thecorn gluten meal does not prohibit germination, it nevertheless does notallow the root structure to develop sufficient that the weed can grow toa healthy plant. As a result, it dies from the lack of root growth. Itis possible that some as of yet unidentified allelopathic compound ispresent in the corn gluten meal. If this be the case, it may also bepossible to isolate the compound, and use it in a highly fortifiedmanner. Alternatively, such a compound could be chemically synthesizedand used or perhaps even produced biotechnically by bacterialsubstances.

As those skilled in the art know, preemergence herbicides are criticalfor application prior to weed emergence. The precise time of applicationwill vary, depending upon the area of the country in which the naturalherbicide of the present invention is applied and the weed speciesinvolved, but in general, for areas of the Midwest, application must beprior to May 1st of any growing season.

It is possible that other extracts of other grain meals may function ina similar manner, although others have not yet been tested. However, onesuch apparent material for possible use would be soybean meal.

The following examples are offered to illustrate the present invention,namely use of corn gluten meal as an effective natural preemergenceherbicide.

EXAMPLE 1

To investigate the effect of cornmeal substances on seed germination, agreenhouse study was conducted. Samples of (1) industrial corn starch,(2) corn gluten meal, (3) dried corn germ, (4) corn seed fiber, and (5)cornmeal were applied to the surface of 16 square inch pots. Thetreatments included a control of each of the material at 7 grams, 14grams, and 28 grams per pot. The study was conducted with both plain andautoclaved samples of each corn component. All pots were seeded withcreeping bentgrass.

The results of this study clearly showed that the component of the cornthat contains the greatest concentration of the inhibitory substance isthe corn gluten meal. All rates of this product completely inhibited theestablishment of creeping bentgrass. Autoclaving has no effect,indicating that the inhibitory substance is heat stable. It was observedin the greenhouse trial that the effect of the corn materials is not tostop germination, but to stop root formation of the germinated seed.Germination occurs, but the seedling dies in a matter of days because ofthe lack of a root system.

EXAMPLE 2

In further greenhouse trials, it was observed that from 6 to 8 grams ofcorn gluten meal on a 16 square inch pot was sufficient to stop theestablishment of creeping bentgrass. Corn gluten meal applied toestablished Kentucky bluegrass (Poa pratensis) had no detrimentaleffects at rates up to 20 grams per 16 square inch pot. In fact, thegluten improves plant growth, likely as a result of nitrogen releasefrom protein. Trials with other plants species have shown that theinhibitory substance in the gluten meal is effective in preventing theestablishment of crabgrass, smartweed, barnyardgrass, Kentuckybluegrass, perennial ryegrass, tall fescue, smooth bromegrass, andbermudagrass seed.

The information gathered from these example studies indicates that anallelopathic compound may exist in corn grain that has the ability toinhibit the establishment of a variety of plant species by stopping rootformation during germination. This compound also seems safe for use onplants that have already been established.

EXAMPLE 3

In the following example, corn gluten meal was compared withMilorganite, a natural and long commercially available nitrogen source.They were compared in a crabgrass germination study.

In particular, crabgrass was seeded at a rate of 0.20 grams in 4"×4"pots and in a preemergence manner, certain levels of addition, namely 0for a control, 2 grams, 4 grams, 6 grams, 8 grams, 10 grams and 12 gramsof both corn gluten meal and Milorganite were added to the surface ofthe crabgrass seeded pots. The pots were grown and watered and thenumber of crabgrass plants were periodically observed. The followingtable illustrates the number of plants observed and the date and time ofobservance.

                  TABLE 1                                                         ______________________________________                                        CRABGRASS CONTROL IN KENTUCKY BLUEGRASS                                       TURF TREATED WITH CORN GLUTEN MEAL AND                                        MILORGANITE                                                                                      0.5    1.0     2.0  4.0                                                 CON-  LBS    LBS     LBS  LBS                                                 TROL  N      N       N    N                                      ______________________________________                                        CORN GLUTEN MEAL                                                                             81      33     36    32   13                                   MILORGANITE    81      75     56    53   24                                   ______________________________________                                    

It can be seen from the above Table that corn gluten meal effectivelyfunctions to selectively inhibit crabgrass germination whereas a commonnatural nitrogen source, long commercially available Milorganite, doesnot act to the same extent.

What is claimed is:
 1. A method for selectively inhibiting growth ofundesirable annual and certain perennial grassy plants in an areacontaining an established plot of desirable grassy plants, said methodcomprising:applying prior to emergence of undesirable grassy plants tosaid area at a concentration of application which .Iadd.selectively.Iaddend.inhibits growth of undesirable plants, corn gluten meal.
 2. Themethod of claim 1 wherein the corn gluten meal is applied atconcentrations of from about 5 lbs./1000 sq. ft. to about 40 lbs/1000 sqft.
 3. The method of claim 2 wherein the corn gluten meal is applied ata concentration of about 20 lbs/1000 sq. ft.
 4. The method of any one ofclaims 1, 2 or 3, wherein the desirable grassy plants are bluegrassturf. .Iadd.
 5. A method for selectively inhibiting growth ofundesirable plants in a plot of desirable plants, said methodcomprising:applying corn gluten meal to said plot, prior to emergence ofsaid undesirable plants, at a concentration of application whichselectively inhibits growth of said undesirable plants by stopping rootformation. .Iaddend. .Iadd.
 6. The method of claim 5 wherein theundesirable plants are annual grassy weeds. .Iaddend. .Iadd.7. Themethod of claim 5 wherein the undesirable plants comprise crabgrass,creeping bentgrass, smart weed, Kentucky bluegrass, perennial ryegrass,smooth bromegrass, barnyard grass, Bermuda grass or tall fescue..Iaddend. .Iadd.8. The method of claim 5 wherein the amount of corngluten meal applied to the plot is from about 5-40 lbs. per 1000 squarefeet. .Iaddend. .Iadd.9. The method of claim 5 wherein the desirableplants are bluegrass turf. .Iaddend.